In high-availability computer systems it is necessary that the usually numerous modules involved in data processing be made identifiable and that, within certain limits, tasks and priorities be assigned to the modules. Said procedures are to be carried out before the startup of the computer system. These goals are accomplished either by providing electronic identification sources, i.e., ROM or other hardware devices, i.e., switches, solder straps, etc., or on the other hand by implementing software-controlled transmissions of appropriate bit masks over the data and address buses. In the latter case, separate decoders are further required for nearly every module; these decoders decode and generate the identification commands from the transmitted signals typically referred to as chip select signals. The possibilities for identification are, however, restricted by the corresponding hardware cost, the capability of the decoders, switches, etc., and by the limited time available for initialization of the system.